BRAF(V600E) mutations and immunohistochemical expression of VE1 protein in low-grade serous neoplasms of the ovary

AIMS: The most common BRAF mutation in ovarian low-grade serous neoplasms (LGSNs) involves substitution of valine by glutamic acid at position 600 (V600E). Small studies have demonstrated high specificity of immunohistochemistry with mutation-specific monoclonal antibody VE1. We sought to investigate expression of VE1 protein in LGSNs and its correlation with BRAF mutation-associated histological features and BRAF mutation status. METHODS AND RESULTS: We reviewed pathology reports and available slides from ovarian serous borderline tumours (SBTs) and low-grade serous carcinomas (LGSCs) diagnosed between 2000-2012. VE1 immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections. Tumours with ≥50% positive cells were considered positive. Statistical analyses were performed using SPSS 24.0. Of 121 LGSNs, there were 73 SBTs, 8 SBTs with micropapillary features (mpSBT), and 40 LGSCs (22 primary, 18 metastatic). VE1 was positive in 52% (38/73) of SBTs and 9% (2/22) of primary LGSCs, and in none of the mpSBTs and metastatic LGSCs (p